This assignment is just to write the hypothesis. Just pick common household items that will be swabbed so that when I do my experiment I can follow the hypothesis. I highlighted in grey, the hypothesis requirements.
Your final project for this class is to design a bacteria experiment and perform the experiment with items from your lab kit. You will need to create a hypothesis that you will submit at the end of week 5. You also need to write a lab report following all the steps of the scientific method that will be due week 11. You will have to have controls and an experimental group. You will have to run multiple tests. You must identify the controls, independent and dependent variables. Measurements and calculations must be in the form of a table. Photographs are required. Click on the View Rubric button within this assignment for information on grading of this assignment.
The materials you need for this experiment are in your lab kit. They are the nutrient agar, 10 petri dishes and sterile swabs.
Everyone in the class has the same materials but no students should have the exact same experiment. You are all going to place the nutrient agar in the petri dishes and swab areas with the sterile swabs, inoculate the petri dishes and grow bacteria. But you will all have different variables and controls. Students will be swabbing different areas around their houses for bacteria testing and comparison. They will be incubating their bacteria for different times or under different temperatures or light. They may or may not be using soaps, bacterial wipes or hand sanitizers in the experiment. Incubation could take place in a high traffic area or a very low traffic area.
Just a few examples:
- compare bacteria growth from swabs taken from inside bathroom door knob and outside bathroom door knob
- compare bacteria growth from one area but at incubated at different temperatures or light
- compare bacteria growth from a keyboard before wiped with hand sanitizer and after wiped with hand sanitizer
I have given you the overview of your experiment, if you are not familiar with inoculating media and culturing bacteria there are many examples on the Internet and Youtube which may also be helpful when you are writing your experimental procedure. When your experiment is complete and you have photographed and recorded your results and written your lab report, pour a 15% bleach solution on your petri dishes and wrap in newspaper and throw them in the garbage.
PLEASE NOTE: You only have enough agar for 10 petri dishes and you want to run multiple trials of your experiment. So do not use all your petri dishes and agar on one trial – save enough so you can do multiple trials. Do not try to incubate the bacteria in your refrigerator.
For ease of testing you should be only testing one variable (the independent variable). Remember your hypothesis needs your independent variable, your control and your dependent variable and must include measurements – TIME AND QUANTITY ex. How long are you incubating for? What do you think you will see? How much (in a number or percentage) difference do you expect to see between the items you are comparing.
You will submit your hypothesis to me in this assignment. Just write your hypothesis in the comment section of this assignment and then submit. Make sure you check MY GRADES for feedback before starting your experiment. If I approve of your hypothesis you will be given 20 points toward your final project. If you need to rework your hypothesis you will not get the full 20 points. Remember your hypothesis should be specific, measureable with not too many variables. So think carefully before you submit it. Your hypothesis is due by Sunday of this week.